Employees and friends affected by the Connecticut shooting at Hartford Distributors Tuesday gather outside the warehouse in Manchester, Conn., Wednesday. The suspect, Omar Thornton, reportedly said he was racially harassed.

Jessica Hill/AP

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In a phone call to his mom after in the early hours of Tuesday morning, the man suspected of shooting eight of his co-workers at Hartford Distributors in Manchester, Conn., reportedly said, "I killed the five racists that were bothering me." Then he took his own life.

The deaths at the beer distributor plant is the largest-scale workplace shooting since the killing of 13 people at Fort Hood last year.

Union officials claim that there's no record of the alleged shooter, Omar Thornton, making any official complaints about racism. Company spokesmen deny that employees harbored racist views.

Reports indicate that, to Thornton at least, race was an issue at Hartford Distributors. He told friends and relatives that coworkers had scrawled racist epithets on a bathroom wall and a hung a stick-figure effigy in a miniature noose.

But criminologist Daniel Kennedy suggests that race is often not the root cause of workplace shootings – even when it is part of the suspect's real or perceived grievances.

"This is far more complicated than an individual claiming a racial basis for all his problems," says Mr. Kennedy, an emeritus professor of criminology at the University of Detroit Mercy. "Even if true, this response is far disproportionate to any slight, which leads you to look more at the internal structure of this guy's thinking than leads you to look at any negative aspects of the organization."

Thornton 'very sensitive about his race'

Managers had confronted Thornton Tuesday morning with video that showed him stealing beer. After agreeing to resign from his job as a truck driver, Thornton stood up, went into the company's kitchenette, then pulled at least one gun from a lunch box and began firing, according to police. All of his victims were white men over the age of 50, the police added.

"Everyone of [the victims] was a person I heard Omar mention," Thornton's girlfriend, Kristi Hannah, told the New York Daily News. "He didn't go around randomly shooting people. He knew these were the people who harassed him."

Thornton, a black man, "was very sensitive about his race," Ms. Hannah said.

"If you called him a n----r, he would go off," she said. "But he kept it inside. He kept it all bottled up."

The facts on workplace violence

Race, however, is often not an issue in workplace violence. Six of 10 incidents of workplace violence involved blacks and whites victimizing members of their own race, according to a 1999 Bureau of Labor Statistics study.

Moreover, blacks are not disproportionately more likely to murder a coworker than people of other races. Between 1997 and 2008, blacks committed 17 percent of the 744 incidents of workplace coworker murder – a number that is roughly in line with blacks' percentage of the US population (13 percent).

Although the US has seen a spate of mass killings in the past two years, workplace homicides have slid during the past decade, falling by more than half since the 1990s – from 1,080 in 1994 to 517 in 2008, according to BLS.

While Thornton may or may not have had a legitimate complaint about racial harassment in the workplace, other facts, including that he committed suicide, point to a more standard profile of a workplace shooter, says Kennedy, the criminologist.

"People who do these kinds of things don't wake up that morning and decide to do it," he says. "They tend to be grievance collectors who remember every slight and … they tend to externalize blame. Whatever happens is not their fault, and they tend to perceive a profound sense of injustice."